Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ 1. OVERVIEW ++ This chapter focuses on general concepts of protein function to lay groundwork for all of the metabolism pathways coming up There are some topics important for Step 1 that we focus on here Enzyme kinetics Muscle contraction Diseases: Marfan's syndrome, cystic fibrosis Try to group proteins into the ones that do something (i.e., enzymes) and the ones that don't do much (e.g., structural proteins) Learning about basics of protein function and nomenclature can help you make educated guesses on difficult questions +++ Structural Proteins ++ Some important diseases arise from defects in structural proteins, as opposed to proteins that carry out more active functions +++ 2. CYTOSKELETAL PROTEINS ++ Intracellular structure and cell motility Microtubules (MTs): In cytosol and cilia — movement of specific things inside the cell Tubulin heterodimers form the basic structure Kinesin and dynein are motor proteins that “walk” along MTs Actin: Cell structure (microfilaments), microvilli, and scaffold for myosin Actin fibrils are the major structural component of muscles and enable contraction Intermediate filaments: Varied, used in histopathology to identify cell types Antimicrobial and anticancer drugs target MTs as “active” in these cell types Vincristine and vinblastine inhibit MT formation to prevent mitosis of cancer cells Paclitaxel “locks” MTs in mitosis so cancer cells can't complete division Colchicine affects neutrophil motility (important for gout) Mebendazole and griseofulvin affect MT formation in parasites and fungi Microtubule defects lead to developmental disorders Kartagener syndrome: Cilia are dysfunctional because of MT motor protein → developmental, reproductive, respiratory problems ++Table Graphic Jump LocationTable 4-1.Intermediate filament stains (review).View Table||Download (.pdf) Table 4-1. Intermediate filament stains (review). Stain Cell type Used to identify Cytokeratin Epithelium Epithelial tissue, e.g., skin, GI, ovarian, squamous cell carcinoma Desmin Muscle Rhabdomyosarcoma, etc. Vimentin Mesenchymal tissue Sarcomas, endometrial carcinoma, renal cell carcinoma, meningioma Neurofilament Neurons Neuroblastoma Glial fibrillary acidic protein (GFAP) Glia (astrocytes) Astrocytoma, glioblastoma ++ Figure 4-1. Cytoskeletal proteins. Graphic Jump LocationView Full Size||Download Slide (.ppt) ++ Figure 4-2. Anti-microtubule drugs. Graphic Jump LocationView Full Size||Download Slide (.ppt) +++ 3. EXTRACELLULAR MATRIX ++ Extracellular space: Provides scaffold to support connective tissue and skin Collagen is a key component (reviewed in Chapter 3) Elastin: Springy substance in organs that need to stretch Like collagen, has glycine, proline, lysine Also like collagen, crosslinking of fibers requires lysyl oxidase Inhibition of lysyl oxidase can cause aortic weakness (mimicking Marfan's syndrome) Differs from collagen on a biochemical level: No hydroxylation Fibrillin: Another elastic protein that complexes with elastin to provide stretch α1-antitrypsin deficiency is due to excessive breakdown of elastin because of overactive elastase → emphysema Lungs primarily affected: Panacinar emphysema Liver also affected: Site of α1-antitrypsin synthesis Liver is damaged due to accumulation of misfolded protein Marfan's ... Your Access profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free a profile for additional features.